The present invention relates to a pull-out guide for domestic appliances. The pull-out guide includes a guide rail, at least one additional rail displaceably mounted relative to the guide rail via a rolling body in a rolling-body cage, and at least one stop configured to limit a displacement path of the at least one additional rail. The at least one stop is configured as a first crosspiece and shaped onto one of the guide rail and the at least one additional rail.
Such pull-out guides are known in numerous embodiments from the state of the art. They frequently consist of a guide rail and at least one running rail. The running rail is displaceably held relative to the guide rail via rolling bodies which are accommodated in rolling-body cages. Pull-out guides are also known comprising a guide rail, a running rail and an interposed middle rail. The guide rail is displaceably held in relation to the middle rail via rolling bodies accommodated in rolling-body cages, and with the middle rail also being displaceably held relative to the running rail via rolling bodies accommodated in a rolling-body cage.
The paths of displacement of the individual rails with respect to one another are precisely defined. These paths in the individual components are usually configured in such a way depending on the pull-out path, the length of the spherical cages or the rolling-body cages and the rail length that path limits provided on the rails will be accessed simultaneously. A displacement of the rolling-body cages or spherical cages between the respective two rails may occur by certain external circumstances during transport of the pull-out guides as a result of vibrations or an unfavourable transport position in the package or also as a result of the presence of a large quantity of lubricant for lubricating the rolling bodies under simultaneous loading of the rails. This leads to the consequence that the rolling-body cage or spherical cage is prematurely moved to one of the stops. This offset may become so large that the pull-out guides cannot be opened and closed completely, or only with a major input of force. In order to produce the full running range of the pull-out guides again, the pull-out guide needs to be stretched, that is, it is pulled or pushed under application of force to its end position. In this process, the rolling bodies need to slide in a certain region because they are unable to reach the end position by mere rolling off.
Such stops for defining the running ranges of the rails, with respect to each other, are arranged on a rail in such a way that they will press the rolling bodies against the track of the opposite rail and therefore produce a wedging effect. This wedging effect leads to a high level of sliding friction, which again leads to a respectively high stretching force that needs to be applied. In the event of a simultaneously occurring lack of lubrication, this wedging effect may even lead to complete blockage of the pull-out guide. Such a lack of lubrication frequently occurs in pull-out guides which are subject to extreme environmental conditions. Examples for such conditions are baking ovens, pyrolysis ovens or dishwashers.
Embodiments of the present disclosure provide for a pull-out guide which can be pushed back or pulled back to its original state after a displacement of a rolling-body cage or a spherical cage with a low amount of stretching force and especially without any blockage.
Thus, an embodiment according to the present disclosure includes a pull-out guide for domestic appliances. The pull-out guide includes a guide rail, at least one additional rail displaceably mounted relative to the guide rail via a rolling body in a rolling-body cage, and at least one stop configured to limit a displacement path of the at least one additional rail. The at least one stop is configured as a first crosspiece and shaped onto one of the guide rail and the at least one additional rail. The at least one stop projects into the displacement path of one of the rolling-body cage and the rolling body, the rolling body being an outer rolling body. The at least one stop projects up to at least half of the radius of the outer rolling body or up to substantially a rotational axis of the outer rolling body, as seen in a direction of displacement.
In accordance with an embodiment of the present disclosure, the at least one stop for limiting the path of displacement of the at least one additional rail is arranged as a cross piece which is shaped on the guide rail or on the at least one additional rail and projects into the path of displacement of the rolling-body cage or of an outer rolling body, as seen in the direction of displacement. The crosspiece projects close to the rotational axis, for example, up to at least half the radius of the rolling body. As a result of the attack of the crosspiece on the rolling-body cage, the likelihood of blockage of one of the rolling bodies is excluded from the outset. If the crosspiece engages on at least half the height of the radius, for example, close to the rotational axis of the rolling body on the rolling body, this will not produce a force component perpendicular to the displacement direction, or only a very low such force, so that the rolling body will not be subject to any likelihood of being pressed from the plane of the displacement direction against one of the running surfaces of the rails.
Embodiments according to the present disclosure are discussed herein and in the appended claims.
According to an embodiment of the present disclosure, the crosspiece is arranged as a bridge shaped transversely to the direction of displacement and interacting in function with the rolling-body cage. From a production standpoint, such a bridge can be shaped very easily in a rail from the outside.
In accordance with another embodiment of the present disclosure, the pull-out guide includes at least one crosspiece which is arranged as a bridge shaped transversely to the direction of displacement and interacting in function with the rolling-body cage. In addition, a further crosspiece protrudes up to and close to the rotational axis, for example, up to the rotational axis of the rolling bodies. This further crosspiece interacts with a rolling body which is on the outside as seen in the direction of displacement. The combination of the two crosspiece embodiments allows an exceptionally reliable limitation of the running path.
In accordance with another embodiment of the present disclosure, the guide rail and the at least one additional rail include several running surfaces extending parallel with respect to one another for several rows of rolling bodies. The several rows of rolling bodies are arranged in the rolling-body cage parallel with respect to each other in the running direction. The crosspieces protrude into the path of displacement of the rolling-body cage and are shaped from a first running surface of one of the guide rails or one of the additional rails, and the crosspieces protruding into the path of displacement of the rolling bodies are shaped on one of the other guide rails parallel to the first running surface or an additional rail. This ensures that the crosspieces used as the running or displacement path limit will not collide with each other during the displacement of the rails relative to one another.
Other aspects of the present disclosure will become apparent from the following descriptions when considered in conjunction with the accompanying drawings.